TOM40 Mediates Mitochondrial Dysfunction Induced by α-Synuclein Accumulation in Parkinson's Disease.

Alpha-synuclein (α-Syn) accumulation/aggregation and mitochondrial dysfunction play prominent roles in the pathology of Parkinson's disease. We have previously shown that postmortem human dopaminergic neurons from PD brains accumulate high levels of mitochondrial DNA (mtDNA) deletions. We now addressed the question, whether alterations in a component of the mitochondrial import machinery -TOM40- might contribute to the mitochondrial dysfunction and damage in PD. For this purpose, we studied levels of TOM40, mtDNA deletions, oxidative damage, energy production, and complexes of the respiratory chain in brain homogenates as well as in single neurons, using laser-capture-microdissection in transgenic mice overexpressing human wildtype α-Syn. Additionally, we used lentivirus-mediated stereotactic delivery of a component of this import machinery into mouse brain as a novel therapeutic strategy. We report here that TOM40 is significantly reduced in the brain of PD patients and in α-Syn transgenic mice. TOM40 deficits were associated with increased mtDNA deletions and oxidative DNA damage, and with decreased energy production and altered levels of complex I proteins in α-Syn transgenic mice. Lentiviral-mediated overexpression of Tom40 in α-Syn-transgenic mice brains ameliorated energy deficits as well as oxidative burden. Our results suggest that alterations in the mitochondrial protein transport machinery might contribute to mitochondrial impairment in α-Synucleinopathies

Outbreak of pandemic influenza A/H1N1 2009 in Nepal

<p>Abstract</p> <p>Background</p> <p>The 2009 flu pandemic is a global outbreak of a new strain of H1N1 influenza virus. Pandemic influenza A (H1N1) 2009 has posed a serious public health challenge world-wide. Nepal has started Laboratory diagnosis of Pandemic influenza A/H1N1 from mid June 2009 though active screening of febrile travellers with respiratory symptoms was started from April 27, 2009.</p> <p>Results</p> <p>Out of 609 collected samples, 302 (49.6%) were Universal Influenza A positive. Among the influenza A positive samples, 172(28.3%) were positive for Pandemic influenza A/H1N1 and 130 (21.3%) were Seasonal influenza A. Most of the pandemic cases (53%) were found among young people with ≤ 20 years. Case Fatality Ratio for Pandemic influenza A/H1N1 in Nepal was 1.74%. Upon Molecular characterization, all the isolated pandemic influenza A/H1N1 2009 virus found in Nepal were antigenically and genetically related to the novel influenza A/CALIFORNIA/07/2009-LIKE (H1N1)v type.</p> <p>Conclusion</p> <p>The Pandemic 2009 influenza virus found in Nepal were antigenically and genetically related to the novel A/CALIFORNIA/07/2009-LIKE (H1N1)v type.</p

Aggregated a-synuclein and complex I deficiency: exploration of their relationship in differentiated neurons

α-Synuclein becomes misfolded and aggregated upon damage by various factors, for example, by reactive oxygen species. These aggregated forms have been proposed to have differential toxicities and their interaction with mitochondria may cause dysfunction within this organelle that contributes to the pathogenesis of Parkinson’s disease (PD). In particular, the association of α-synuclein with mitochondria occurs through interaction with mitochondrial complex I and importantly defects of this protein have been linked to the pathogenesis of PD. Therefore, we investigated the relationship between aggregated α-synuclein and mitochondrial dysfunction, and the consequences of this interaction on cell survival. To do this, we studied the effects of α-synuclein on cybrid cell lines harbouring mutations in either mitochondrial complex I or IV. We found that aggregated α-synuclein inhibited mitochondrial complex I in control and complex IV-deficient cells. However, when aggregated α-synuclein was applied to complex I-deficient cells, there was no additional inhibition of mitochondrial function or increase in cell death. This would suggest that as complex I-deficient cells have already adapted to their mitochondrial defect, the subsequent toxic effects of α-synuclein are reduced

Withaferin a-induced apoptosis in human breast cancer cells is mediated by reactive oxygen species

Withaferin A (WA), a promising anticancer constituent of Ayurvedic medicinal plant Withania somnifera, inhibits growth of MDA-MB-231 and MCF-7 human breast cancer cells in culture and MDA-MB-231 xenografts in vivo in association with apoptosis induction, but the mechanism of cell death is not fully understood. We now demonstrate, for the first time, that WA-induced apoptosis is mediated by reactive oxygen species (ROS) production due to inhibition of mitochondrial respiration. WA treatment caused ROS production in MDA-MB-231 and MCF-7 cells, but not in a normal human mammary epithelial cell line (HMEC). The HMEC was also resistant to WA-induced apoptosis. WA-mediated ROS production as well as apoptotic histone-associated DNA fragment release into the cytosol was significantly attenuated by ectopic expression of Cu,Zn-superoxide dismutase in both MDA-MB-231 and MCF-7 cells. ROS production resulting from WA exposure was accompanied by inhibition of oxidative phosphorylation and inhibition of complex III activity. Mitochondrial DNA-deficient Rho-0 variants of MDA-MB-231 and MCF-7 cells were resistant to WA-induced ROS production, collapse of mitochondrial membrane potential, and apoptosis compared with respective wild-type cells. WA treatment resulted in activation of Bax and Bak in MDA-MB-231 and MCF-7 cells, and SV40 immortalized embryonic fibroblasts derived from Bax and Bak double knockout mouse were significantly more resistant to WA-induced apoptosis compared with fibroblasts derived from wild-type mouse. In conclusion, the present study provides novel insight into the molecular circuitry of WA-induced apoptosis involving ROS production and activation of Bax/Bak. © 2011 Hahm et al

Inhibition of Dengue Virus Entry and Multiplication into Monocytes Using RNA Interference

Prevention and treatment of dengue infection remain a serious global public health priority. Extensive efforts are required toward the development of vaccines and discovery of potential therapeutic compounds against the dengue viruses. Dengue virus entry is a critical step for virus reproduction and establishes the infection. Hence, the blockade of dengue virus entry into the host cell is an interesting antiviral strategy as it represents a barrier to suppress the onset of infection. This study was achieved by using RNA interference to silence the cellular receptor, and the clathrin mediated endocytosis that enhances the entry of dengue virus in monocytes. Results showed a marked reduction of infected monocytes by flow cytometry. In addition, both intracellular and extracellular viral RNA load was shown to be reduced in treated monocytes when compared to untreated monocytes. Based on these findings, this study concludes that this therapeutic strategy of blocking the virus replication at the first stage of multiplication might serve as a hopeful drug to mitigate the dengue symptoms, and reduction the disease severity

Genome sequence analysis of Helicobacter pylori strains associated with gastric ulceration and gastric cancer

<p>Abstract</p> <p>Background</p> <p>Persistent colonization of the human stomach by <it>Helicobacter pylori </it>is associated with asymptomatic gastric inflammation (gastritis) and an increased risk of duodenal ulceration, gastric ulceration, and non-cardia gastric cancer. In previous studies, the genome sequences of <it>H. pylori </it>strains from patients with gastritis or duodenal ulcer disease have been analyzed. In this study, we analyzed the genome sequences of an <it>H. pylori </it>strain (98-10) isolated from a patient with gastric cancer and an <it>H. pylori </it>strain (B128) isolated from a patient with gastric ulcer disease.</p> <p>Results</p> <p>Based on multilocus sequence typing, strain 98-10 was most closely related to <it>H. pylori </it>strains of East Asian origin and strain B128 was most closely related to strains of European origin. Strain 98-10 contained multiple features characteristic of East Asian strains, including a type s1c <it>vacA </it>allele and a <it>cagA </it>allele encoding an EPIYA-D tyrosine phosphorylation motif. A core genome of 1237 genes was present in all five strains for which genome sequences were available. Among the 1237 core genes, a subset of alleles was highly divergent in the East Asian strain 98-10, encoding proteins that exhibited <90% amino acid sequence identity compared to corresponding proteins in the other four strains. Unique strain-specific genes were identified in each of the newly sequenced strains, and a set of strain-specific genes was shared among <it>H. pylori </it>strains associated with gastric cancer or premalignant gastric lesions.</p> <p>Conclusion</p> <p>These data provide insight into the diversity that exists among <it>H. pylori </it>strains from diverse clinical and geographic origins. Highly divergent alleles and strain-specific genes identified in this study may represent useful biomarkers for analyzing geographic partitioning of <it>H. pylori </it>and for identifying strains capable of inducing malignant or premalignant gastric lesions.</p

The Characterization of Helicobacter pylori DNA Associated with Ancient Human Remains Recovered from a Canadian Glacier

Helicobacter pylori is a gram-negative bacterium that colonizes the stomach of nearly half of the world's population. Genotypic characterization of H. pylori strains involves the analysis of virulence-associated genes, such as vacA, which has multiple alleles. Previous phylogenetic analyses have revealed a connection between modern H. pylori strains and the movement of ancient human populations. In this study, H. pylori DNA was amplified from the stomach tissue of the Kwäday Dän Ts'ìnchi individual. This ancient individual was recovered from the Samuel Glacier in Tatshenshini-Alsek Park, British Columbia, Canada on the traditional territory of the Champagne and Aishihik First Nations and radiocarbon dated to a timeframe of approximately AD 1670 to 1850. This is the first ancient H. pylori strain to be characterized with vacA sequence data. The Tatshenshini H. pylori strain has a potential hybrid vacA m2a/m1d middle (m) region allele and a vacA s2 signal (s) region allele. A vacA s2 allele is more commonly identified with Western strains, and this suggests that European strains were present in northwestern Canada during the ancient individual's time. Phylogenetic analysis indicated that the vacA m1d region of the ancient strain clusters with previously published novel Native American strains that are closely related to Asian strains. This indicates a past connection between the Kwäday Dän Ts'ìnchi individual and the ancestors who arrived in the New World thousands of years ago

Role of Alpha-Synuclein Protein Levels in Mitochondrial Morphology and Cell Survival in Cell Lines

α-Synuclein is highly associated with some neurodegeneration and malignancies. Overexpressing wild-type or mutant α-synuclein promotes neuronal death by mitochondrial dysfunction, the underlying mechanisms of which remain poorly defined. It was recently reported that α-synuclein expression could directly lead to mitochondrial fragmentation in vitro and in vivo, which may be due to α-synuclein localization on mitochondria. Here, we applied a double staining method to demonstrate mitochondrial morphogenetic changes in cells overexpressed with α-synuclein. We show that mitochondrial localization of α-synuclein was increased following its overexpression in three distinct cell lines, including HeLa, SH-SY5Y, and PC12 cells, but no alteration in mitochondrial morphology was detected. However, α-synuclein knockdown prevents MPP+-induced mitochondrial fragmentation in SH-SY5Y and PC12 cells. These data suggest that α-synuclein protein levels hardly affect mitochondrial morphology in normal cell lines, but may have some influence on that under certain environmental conditions